Abstract
OBJECTIVE: Hyrtl's anastomosis, an intra-arterial shunt, serves a protective function in singleton placentas. Our team previously documented a case of a monochorionic (MC) twin placenta lacking Hyrtl's anastomosis. However, research on the impact of absent Hyrtl's anastomosis in twin placentas remains limited. METHODS: In the present study, we perfused over 70 cases of MC placentas and identified three additional cases exhibiting the same characteristics. RESULTS: The absence of Hyrtl's anastomosis was found to be present in two cases with severe placental territory discordance and one case of a MC triamniotic pregnancy with reversed arterial perfusion sequence, all of which resulted in uneventful pregnancy courses. CONCLUSION: The absence of Hyrtl's anastomosis appears to have a protective effect in MC placentas, contrary to its effect in singleton placentas.